From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BEE3C433B4 for ; Wed, 5 May 2021 13:39:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0B742613C3 for ; Wed, 5 May 2021 13:39:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B742613C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 62F746B006C; Wed, 5 May 2021 09:39:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B6D66B006E; Wed, 5 May 2021 09:39:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3E2666B0070; Wed, 5 May 2021 09:39:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0119.hostedemail.com [216.40.44.119]) by kanga.kvack.org (Postfix) with ESMTP id 1C4F76B006C for ; Wed, 5 May 2021 09:39:14 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C79D7180AD830 for ; Wed, 5 May 2021 13:39:13 +0000 (UTC) X-FDA: 78107283786.06.4F2F0C3 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf17.hostedemail.com (Postfix) with ESMTP id C90AC40002F4 for ; Wed, 5 May 2021 13:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620221953; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IHQUE4RBuZmI4g/5aOXOPIjM70ZyTC143fCzVAJ8P/8=; b=IzfXabDhlFkN2KkOKsWJJIc0gsQUiIVy/r7T9flLxuwbgYWfjdzoPQnQd9J8BgvhA7UV9R FluEaCPMO8eUJRAjK/rcsswg2o1Tsd08GsfcIgbHn9VakY9HV6BJ/+6UEKwuf4vfqdos77 3ObNcxeicmYDQxtkIgXIz0axfDyypSs= Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-443-vXEmIFa3NzqzUwrvNPUTSg-1; Wed, 05 May 2021 09:39:11 -0400 X-MC-Unique: vXEmIFa3NzqzUwrvNPUTSg-1 Received: by mail-ed1-f71.google.com with SMTP id r19-20020a05640251d3b02903888eb31cafso859045edd.13 for ; Wed, 05 May 2021 06:39:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:organization:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=IHQUE4RBuZmI4g/5aOXOPIjM70ZyTC143fCzVAJ8P/8=; b=NlTUwc44ZRKK6azlkIRI6oP40qsXvdI6NTJ/muFz1k/rQuCFg81tkTYmbPwFy7MT05 +lH5rGGE+z7Q+jNKyJV+5kp6rN1mwfc/YclybPa2TJlYoCfX74TX7RxFKX1xvikTpj2I Ywc2k/Z9YvGegskxG9McI9J6fj3TNqnDCjX89g3YyHz7Ir6jgoRCzgrrfFoo50jFi2qP nDa2Wgge2M7d2BWIBMAxbH3EAYaLAd4nv5lv78TyUlX4wrp0PJJxGKIUBPFfDx6fMGwd xg0sZEc41r9CQGPKlTM27z22Qer1u+8JBKiJi20FHjxAlGGkRLv9c6JeWSGsUt7nBeGo U9dA== X-Gm-Message-State: AOAM530enVAJW0RmmZYEIOjAx6AMnk8ahO+aZeeZrCkUMsCeDavOXMcg scRvE67Eyf/cagzUW+TOMwcjGmTAwSCGgmPydINb43cbp5Fl+7sqUQKfinVS2/wsoRsaUPteGrP +ZN0mT30sW4wkpEcC7UWFsHNxaWfTYi4tCnmQ+eb2TQ495b65NQUoK40thoI= X-Received: by 2002:a17:906:2406:: with SMTP id z6mr3444016eja.396.1620221950232; Wed, 05 May 2021 06:39:10 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxGWyxHBPyyOetZHpx601TcawWH0Fo+idEg5VdUHFvJAR1tTdcZpi84XXPEA0gN5zGGPMwDGA== X-Received: by 2002:a17:906:2406:: with SMTP id z6mr3443980eja.396.1620221950000; Wed, 05 May 2021 06:39:10 -0700 (PDT) Received: from [192.168.3.132] (p5b0c63bc.dip0.t-ipconnect.de. [91.12.99.188]) by smtp.gmail.com with ESMTPSA id p21sm16699366edw.18.2021.05.05.06.39.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 May 2021 06:39:09 -0700 (PDT) To: Michal Hocko , Andrew Morton Cc: linux-kernel@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , Alexey Dobriyan , Mike Rapoport , "Matthew Wilcox (Oracle)" , Oscar Salvador , Roman Gushchin , Alex Shi , Steven Price , Mike Kravetz , Aili Yao , Jiri Bohac , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , Naoya Horiguchi , linux-hyperv@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20210429122519.15183-1-david@redhat.com> <20210429122519.15183-4-david@redhat.com> <0710d8d5-2608-aeed-10c7-50a272604d97@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v1 3/7] mm: rename and move page_is_poisoned() Message-ID: <57ac524c-b49a-99ec-c1e4-ef5027bfb61b@redhat.com> Date: Wed, 5 May 2021 15:39:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IzfXabDh; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf17.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=david@redhat.com X-Rspamd-Server: rspam03 X-Stat-Signature: 3ihhx7j88rb84og34cz46e9r5uocghqo X-Rspamd-Queue-Id: C90AC40002F4 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf17; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620221948-456941 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: >> Long story short, this should be good enough for the cases we actually= can >> handle? What am I missing? >=20 > I am not sure I follow. My point is that I fail to see any added value > of the check as it doesn't prevent the race (it fundamentally cannot as > the page can be poisoned at any time) but the failure path doesn't > put_page which is incorrect even for hwpoison pages. Oh, I think you are right. If we have a page and return NULL we would=20 leak a reference. Actually, we discussed in that thread handling this entirely=20 differently, which resulted in a v7 [1]; however Andrew moved forward=20 with this (outdated?) patch, maybe that was just a mistake? Yes, I agree we should revert that patch for now. Regarding the race comment: AFAIU e.g., [2], it's not really a problem=20 with a race, but rather some corner case issue that can happen if we=20 fail in memory_failure(). [1] https://lkml.kernel.org/r/20210406104123.451ee3c3@alex-virtual-machin= e [2]=20 https://lkml.kernel.org/r/20210331015258.GB22060@hori.linux.bs1.fc.nec.co= .jp --=20 Thanks, David / dhildenb